Safety Standards. of the Nuclear Safety Standards Commission (KTA) Monitoring the Discharge of Radioactive Substances from Research Reactors

Transcription

1 Safety Standards of the Nuclear Safety Standards Commission (KTA) KTA 1507 ( ) Monitoring the Discharge of Radioactive Substances from Research Reactors (Überwachung der Ableitungen radioaktiver Stoffe bei Forschungsreaktoren) If there is any doubt regarding the information contained in this translation, the German wording shall apply. The previous versions of this safety standard were issued in and Editor: KTA-Geschaeftsstelle c/o Bundesamt fuer kerntechnische Entsorgungssicherheit (BfE) Willy-Brandt-Str Salzgitter Germany Telephone +49 (0) Telefax +49 (0)

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3 KTA SAFETY STANDARD November 2017 Monitoring the Discharge of Radioactive Substances from Research Reactors Previous versions of this safety standard: (BAnz No. 172a of September 15, 1998) (BAnz No. 125a of July 7, 1984) (BAnz. of January 23, 2013) KTA 1507 Contents Basic Principles Scope Definitions Monitoring the Radioactive Substances Discharged with Vent Air during Specified Normal Operation General Requirements Radioactive Noble Gasses Radionuclides Bound to Aerosol Particles Radioactive Gaseous Iodine Tritium Radioactive Strontium Alpha Emitters Carbon Sampling Non-central Monitoring of Emissions Monitoring the Radioactive Substances Discharged with Vent Air during Design Basis Accidents General Requirements Radioactive Noble Gasses Radionuclides Bound to Aerosol Particles Radioactive Gaseous Iodine Tritium Sampling Monitoring of Radioactive Substances Discharged with Water Radioactively Contaminated Waste Water Cooling Water (Intermediate Cooling Circuits) Design and Construction of Monitoring Equipment General Requirements for Stationary Monitoring Equipment Special Requirements for Stationary Measurement Equipment for Monitoring the Discharge of Radioactive Substances during Design Basis Accidents Maintenance of Stationary Monitoring Equipment Servicing and Repair Tests Removal of Defects Test certificates Measurement Results Documentation Report to the Proper Authorities Appendix A Instruction for Preparing Monthly, Quarterly and Annual Mixture Samples for the Detailed Assessment Measurements Appendix B Regulations Referred to in this Safety Standard PLEASE NOTE: Only the original German version of this safety standard represents the joint resolution of the 35-member Nuclear Safety Standards Commission (Kerntechnischer Ausschuss, KTA). The German version was made public in the Federal Gazette (Bundesanzeiger) on February 5, Copies of the German versions of the KTA safety standards may be mail-ordered through the Wolters Kluwer Deutschland GmbH (info@wolterskluwer.de). Downloads of the English translations are available at the KTA website ( All questions regarding this English translation should please be directed to the KTA office: KTA-Geschaeftsstelle c/o BfE, Willy-Brandt-Strasse 5, D Salzgitter, Germany or kta-gs@bfe.bund.de

4 Comments by the Editor: Taking into account the meaning and usage of auxiliary verbs in the German language, in this translation the following agreements are effective: shall indicates a mandatory requirement, shall basically is used in the case of mandatory requirements to which specific exceptions (and only those!) are permitted. It is a requirement of the KTA that these exceptions - other than those in the case of shall normally - are specified in the text of the safety standard, shall normally indicates a requirement to which exceptions are allowed. However, exceptions used shall be substantiated during the licensing procedure, should indicates a recommendation or an example of good practice, may indicates an acceptable or permissible method within the scope of this safety standard.

5 KTA 1507 Page 5 Basic Principles (1) The safety standards of the Nuclear Safety Standards Commission (KTA) have the task of specifying those safety-related requirements which shall be met with regard to precautions to be taken in accordance with the state of science and technology against damage arising from the construction and operation of the plant (Sec. 7 para. 2 subpara. 3 Atomic Energy Act - AtG) in order to attain the protective goals specified in AtG and the Radiological Protection Ordinance (StrlSchV). (2) The stationary and mobile radiation protection instrumentation has, among others, the dual purpose of protecting persons inside and outside of the plant from ionizing radiation and of verifying the specified normal functioning of the equipment for a) retaining solid, liquid and gaseous radioactive substances inside the designated enclosures, b) handling and the controlled conduction of radioactive substances within the plant, and c) monitoring the discharge of radioactive substances. Safety standard series KTA 1500 specifies detailed safety related requirements regarding this radiation protection instrumentation. (3) The present safety standard KTA 1507 contains the requirements that apply to the technical equipment and the supplementary administrative measures that are considered necessary for monitoring the discharge of radioactive substances with air and water in research reactors during specified normal operation and in the case of design basis accidents. (4) Monitoring the discharge of radioactive substances contributes to meeting the requirements of Secs. 6, 47 and 48 StrlSchV, which specifically specify that it must be ensured a) that any radiation exposure or contamination of man and environment is minimized and, even if below the respective limits specified in StrlSchV, is kept as low as possible taking into account the state of the art and all circumstances of the individual case (Sec. 6 para. 2 StrlSchV), b) that no unmonitored discharge of radioactive substances into the environment will occur (Sec. 47 para. 1 sentence 2 StrlSchV, and c) that discharges are monitored and reported to the proper authority at least once a year, specifying their kind and activity (Sec. 48 para. 1 StrlSchV). The corresponding monitoring equipment must meet the requirements of Sec. 67 StrlSchV. (5) The tasks of monitoring the discharge of radioactive substances comprises a) the detailed assessment of the discharged radioactive substances, thus providing a basis for evaluating the radiological effects, and b) the automatic initiation of alarm signals. (6) In addition to meeting the requirements of this safety standard, the federal Water Resources Act (WHG) and the water act of the respective federal State (Bundesland) shall also be fulfilled. (7) When discharging waste water into a public sewage system, the individual requirements and restrictions specified in communal statutory law shall be taken into consideration. 1 Scope (1) This safety standard shall apply to the equipment and facilities used for monitoring the discharge of gaseous substances, substances bound to aerosol particles and liquid radioactive substances from stationary research reactors with a power larger than 50 kw during specified normal operation and in the case of design basis accidents including the discharge from all plant components included in the nuclear license. Examples for such plant components are neutron conductors, cold and hot neutron sources and irradiation facilities. (2) In the case of mobile research reactors or research reactors with a power less than or equal to 50 kw and of zero power reactors, e.g. training reactors and critical assemblies, the present safety standard should be applied only to the extent that is reasonable taking all circumstances of the individual case into account. (3) Whenever liquid radioactive substances are delivered to authorized third parties, e.g., central decontamination facilities or State collection facilities, the monitoring of these substances is not subject to the requirements of the present safety standard. Secs. 69 and 70 StrlSchV pertain specifically to the transfer of radioactive substances. 2 Definitions (1) Bleed water Bleed water is that portion of the circulating coolant that is discharged from the secondary and tertiary cooling circuits in order to keep the amount of substances contained in the coolant within permissible limits. (2) Discharge of radioactive substances The discharge of radioactive substances is the intentional release of liquid radioactive substances, radioactive substances bound to aerosol particles or gaseous radioactive substances from the plant along designated paths. (3) Discrimination of measurement equipment The discrimination of measurement equipment is the ratio of the displayed value of the measurement parameter and the actual value of this measurement parameter. (4) Specified normal operation Specified normal operation comprises a) operating processes for which the plant, assuming the able function of all systems (fault free condition), is intended and suited (normal operation); b) operating processes which occur as a cause of a malfunctioning of plant components or systems (fault condition), insofar as safety related reasons do not stand in the way of continuing operation (abnormal operation); c) maintenance procedures (inspection, servicing, repair). (5) Detailed assessment of radioactive substances The detailed assessment is a special form of monitoring consisting of identifying, and determining the activity of, the radionuclides or radionuclide groups discharged over a given time span. For detailed assessment measured value is used. The measurement uncertainty is indicated separately. (6) Cesium-137 equivalent (water) Cesium-137 equivalent is a calculated measurement parameter in units of Becquerel per cubic meter (Bq/m 3 ). It is determined by multiplying the measured gamma count rate of a measurement source with a ratio of activity concentration and gamma count rate determined under the same geometric conditions for a standard solution of Cesium-137.

6 KTA 1507 Page 6 (7) Double determination Double determination is the activity measurement on aliquot portions of a representative sample after having performed identical preparatory procedural steps on these portions (e.g., concentration by evaporation, radio-chemical separation). (8) Decision threshold The decision threshold is a calculated value of a parameter (e.g., activity, activity concentration, specific activity) for the comparison with a measurement value in order to decide whether the parameter has contributed to the measurement or has had a zero effect. (1) Decision thresholds are determined in accordance with DIN ISO (2) Application examples are given in report KTA-GS 82. (9) Research reactor A research reactor is a nuclear reactor which is operated exclusively for at least one of the following purposes: a) utilization of the radiation produced by nuclear fission, b) measurement of nuclear physics data, or c) measurement of reactor physics data. (10) Total alpha activity The total alpha activity is the radioactivity determined by an integral measurement of the alpha particles emitted by a radioactive substance which is, then, related to the reference nuclide used for calibrating the measurement equipment. (11) Total beta activity The total beta activity is the radioactivity determined by an integral measurement of the beta particles emitted by a radioactive substance which is, then, related to the reference nuclide used for calibrating the measurement equipment. (12) Overall dissipation factor (sampling airborne substances) The overall dissipation factor is a correction factor to be applied to the determined discharge of airborne radioactive substances. It is, essentially, comprised of factors from changes of the activity concentrations of airborne radioactive substances arising from a) a determination in a partial air stream with a sampling rake, b) a non-isokinetic sampling, c) transport through the sampling pipe (pipe factor), and d) the transport in the accumulating and measurement equipment. (13) Calibration of the measurement equipment for radiation monitoring The calibration of the measurement equipment for radiation monitoring is the determination of the relationship between the value defined by specific norms (e.g., activity of the calibration source) and the displayed value (e.g., count rate) of the measurement parameter. (14) Measurement medium The measurement medium is a sample taken from the medium to be monitored that possibly after an engineering procedural treatment such as heating, filtration, dilution flows through the measurement volume (i.e., that region for which the discrimination of the respective measurement equipment was determined during calibration). (15) Mixture sample A mixture sample is a mixture of individual samples or cumulative samples, or of parts of these samples, taken within a specified time period. (16) Detection limit The detection limit is a calculated value of a measurement parameter (e.g., activity, activity concentration, specific activity) that shall normally be compared to a predetermined reference value in order to decide whether or not the measuring procedure is suitable for a particular measurement task. (1) Decision thresholds are determined in accordance with DIN ISO (2) Application examples are given in report KTA-GS 82. (17) Representative sample (of discharges) A representative sample is a particular sample the examination of which allows determining the discharged radioactive substances according to their kind and activity. (18) Pipe factor The pipe factor is the ratio determined in a stationary condition of the activity concentration of a radionuclide or radionuclide group at the entry port of a sampling probe and the activity concentration at the connection point of the accumulating or measurement equipment for monitoring the activity concentration of gaseous radionuclides or radionuclides bound to aerosol particles. (19) Cumulative sample A cumulative sample is a sample accumulated by continuous or quasi-continuous sampling within a specified time period. (20) Threshold value A threshold value is a plant-internal value the exceedance of which would require taking certain measures. (21) Design basis accident A design basis accident is a chain of events which, upon its occurrence, would require interruption of plant operation or of a task activity for reasons of safety, and which shall be considered in the plant design or for which, with regard to the task activity, protective measures shall be provided. (22) Monitoring Monitoring is a collective term for all different types of a controlled determination of physical parameters and includes comparing the results with specified values. Notes: (1) Monitoring is performed a) by continuous measurements or b) by analyses of samples (e.g. in a laboratory) or c) by a combination of measurement values and always in connection with the comparison of the results with specified values of the physical parameters (e.g., licensed limit values, operational values). (2) To verify compliance with licensed limit values the upper limit of the confidence interval is applied. (23) Confidence interval The confidence interval is the interval that contains the true value of the measurement parameter with a specified probability.

7 KTA 1507 Page 7 The limits of the confidence interval are determined in accordance with DIN ISO Monitoring the Radioactive Substances Discharged with Vent Air during Specified Normal Operation 3.1 General Requirements (1) The radioactive substances discharged during specified normal operation shall be determined according to kind and activity in accordance with the requirements specified in this Section 3. With regard to the accumulation and measurement procedures, the following nuclides and nuclide groups shall be differentiated between: a) radioactive noble gasses, b) radionuclides bound to aerosol particles, c) radioactive gaseous iodine, d) tritium, e) radioactive strontium, f) alpha emitters, and g) carbon-14. (2) With regard to monitoring the discharge of radioactive substances, the continuous or non-continuous sampling, the measuring and the accumulating of samples shall normally be performed in a partial air stream of the vent air. The volumetric flow of all partial air streams shall be continuously monitored. (3) The volumetric flow of the vent air shall be measured and recorded continuously; the measurement uncertainty of the volumetric flow measurement shall be specified. (4) With regard to the continuous measurement of radionuclides bound to aerosol particles and radioactive gaseous iodine, a deviation by more than 20 % of the volumetric flow of the partial air stream from its nominal value shall set off an alarm in the control room. (5) Regarding the detailed assessment of radionuclides bound to aerosol particles, radioactive gaseous iodine, tritium, radioactive strontium, carbon-14 and other alpha emitters, the volumetric flow shall be measured and a deviation by more than 20 % of the volumetric flow of the partial air stream from its nominal value shall set off an alarm in the control room. This requirement may be dispensed with if piston pumps are used. 3.2 Radioactive Noble Gasses Continuous measurement (1) The radioactive noble gasses discharged with vent air shall be continuously determined by beta-measurements and shall be continuously monitored with respect to a threshold value. This requires at least one continuous measurement and recording of the total beta activity concentration in connection with the continuous measurement and recording of the volumetric flow of vent air. (2) In order to prevent any falsification of measurement values, a high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN shall be installed upstream of the measurement equipment. (3) The detection limit of the measurement equipment for determining the activity concentration shall not exceed Bq/m 3 with respect to xenon-133 for a measurement duration of ten minutes. (4) Taking the volumetric flow of vent air into account, the upper end of the measurement range shall be such that, relative to the vent air volume discharged in a 24 h period, it is possible to determine discharge rates at least up to one tenth of the licensed annual limit value. (5) If the design of the activity measurement equipment does not provide for redundancy, the activity discharge from radioactive noble gasses shall be estimated for the duration of any outage duration of this measurement equipment; given a known volumetric flow of vent air, the estimation shall be based on some other permanently installed instrumentation. The outage duration may not exceed a time period of 3 days Detailed assessment (1) The radioactive noble gasses discharged with vent air shall be subjected to a detailed assessment. This requires that a beta measurement is performed to determine the discharge rate of the total beta activity specified under Section para. 1 taking the proportion of each individual nuclide in the nuclide composition into account. (2) The non-continuous determination of the nuclide composition shall be performed on single representative samples taken in quarterly intervals. These samples shall be analyzed without delay. In this context, the radionuclides listed in Table 3-1 shall be taken into account. Argon-41 Krypton-85 Krypton-85m Krypton-87 Krypton-88 Radionuclides Xenon-131m Xenon-133 Xenon-133m Xenon-135 Xenon-135m Xenon-138 Table 3-1: Radionuclides to be taken into account in the detailed assessment of the activity of radioactive noble gasses discharged with vent air (3) The detection limit for the determination of the individual nuclides specified in para. 2 shall not exceed a value of Bq/m 3 with respect to xenon-133. Any undetected nuclides of Table 3-1 shall be listed with the corresponding value of the decision thresholds and detection limits achieved in the individual measurements with the measurement equipment. (4) If the measurement specified in para. 2 detects xenon-133 with an activity concentration exceeding Bq/m 3, however no krypton-85, then, after a decay period of at least two days, a second analysis of the sample shall be performed with regard to determining the activity concentration of krypton-85. (5) In addition to sampling in quarterly intervals, further representative samples shall, without delay, be taken and analyzed if the threshold value specified in Section para. 1 is reached and registers for the duration exceeding 30 minutes. For as long as this threshold value continues to register, a sample shall be taken at least every 24 hours and its nuclide composition determined without delay. (6) In the case of non-continuous sampling, the nuclide composition shall be assumed as being constant in the interim period between two consecutive samplings and at the level of the second measurement. (7) As an alternative to the requirements specified under paras. 2 through 6, the activity of discharged radioactive noble gasses may also be determined by continuous nuclide-specific measurements. The detailed assessment shall be based on the nuclide spectra determined in daily intervals. When evaluating the daily nuclide spectra, the detection limit of the measurement equipment shall not exceed a value of Bq/m 3 for xenon-133.

8 KTA 1507 Page 8 (8) Any additional radioactive noble gas nuclides verified in the stack discharge shall individually be recorded in the report form (cf. Figure 8-1) under the heading "Other noble gasses". 3.3 Radionuclides Bound to Aerosol Particles Continuous measurement (1) The radionuclides bound to aerosol particles discharged with vent air shall be monitored continuously. This requires that the radionuclides bound to aerosol particles shall be continuously accumulated from a partial air stream by deposition on a high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN ; the activity of the high-efficiency particulate air filter shall be measured during accumulation. From this measurement value the activity concentration shall be determined and shall be documented. (2) The measurement equipment shall be designed such that, assuming a previously uncontaminated high-efficiency particulate air filter and a short-time exposure to a cesium-137 equivalent with a time integral of 4 (Bq/m 3 ) h, the detection limit for the display of the measurement parameter "Activity on the filter" or Increase of activity on the filter will be exceeded in no more than one hour. The requirements specified regarding the detection limit apply to the plant independent verification of the equipment characteristics. (3) The high-efficiency particulate air filter shall be monitored for an activity level the exceedance of which would indicate that the filter must be exchanged. At this level it shall still be possible at a nominal volumetric flow of the vent air and a corresponding filter loading to be able to detect a discharge of Bq within one hour with a measurement uncertainty of less than 20 %. (4) If the design of the measurement equipment for monitoring the discharge of radionuclides bound to aerosol particles does not provide for redundancy, the respective discharge shall be estimated for the duration of any outage duration of this measurement equipment; given a known volumetric flow of vent air, the estimation shall be based on some other permanently installed instrumentation, e.g., for monitoring the room atmosphere. The outage duration may not exceed a time period of 3 days. (5) The requirement for a continuous measurement may be dispensed with, provided, a) the radionuclides bound to aerosol particles are retained by filtering the entire vent air with high-efficiency particulate air filters of at least Filter Class E12 in accordance with DIN EN and the functional capability of the retaining equipment is monitored, or b) a continuous measurement of the activity discharge from radioactive gaseous iodine is performed as specified in Section Detailed assessment (1) The activity of radionuclides bound to aerosol particles discharged with vent air shall be subjected to a detailed assessment. This requires that these substances are continuously accumulated by deposition on a high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN (2) The accumulation period shall not exceed one week; the time elapsed between start of accumulation and start of measurement shall be accounted for by applying a corresponding correction for radioactive decay. (3) The high-efficiency particulate air filters shall be analyzed by gamma spectrometric measurements within two days after removal of the filter. In this context, the radionuclides listed in Table 3-2 shall be taken into account. (4) The high-efficiency particulate air filter specified under para. 1 shall be analyzed without delay whenever the threshold value specified under Section para. 1 is reached and has registered for the duration of more than 30 minutes. (5) The detection limit of the measurement equipment for determining the activity concentration shall not exceed Bq/m 3 with respect to cesium-137. Any undetected radionuclides of Table 3-2 shall be listed with the value of the decision thresholds and detection limits achieved in the individual measurement with the measurement equipment. Chromium-51 Manganese-54 Cobalt-58 Iron-59 Cobalt-60 Zinc-65 Zirconium-95 Niobium-95 Ruthenium-103 Ruthenium-106 Radionuclides Silver-110m Antimony-124 Antimony-125 Iodine-131 Cesium-134 Cesium-137 Barium-140 Lanthanum-140 Cerium-141 Cerium-144 Table 3-2: Radionuclides to be taken into account in the detailed assessment of the activity of radionuclides bound to aerosol particles discharged with vent air (6) Any additional radionuclides bound to aerosol particles verified in the stack discharge shall individually be recorded in the report form (cf. Figure 8-1) under the heading "Other γ-radiating radionuclides" or Other α-emitting radionuclides. 3.4 Radioactive Gaseous Iodine Continuous measurements (1) The radioactive gaseous iodine discharged with vent air shall be monitored continuously. This requires that the radioactive iodine is continuously accumulated from a partial air stream on an iodine filter and that the filter is measured during accumulation for the deposited activity of iodine-131 (reference nuclide). The activity concentration shall be determined from this measurement value and shall be recorded. (2) The measurement equipment shall be designed such that, assuming a previously uncontaminated iodine filter and a shorttime exposure to iodine-131 with a time integral of 2 (Bq/m 3 ) h, the display of the measurement parameter "Activity on the filter" or Increase of activity on the filter will exceed the detection limit in no more than one hour. The requirements specified regarding the detection limit apply to the plant independent verification of the equipment characteristics. (3) The iodine filter shall be monitored for an activity level the exceedance of which would indicate that the filter must be exchanged. At this level it shall still be possible at a nominal volumetric flow of vent air and a corresponding filter loading to be able to detect a discharge of Bq within one hour with a measurement uncertainty of less than 20 %. (4) In order to prevent any falsification of the measurement values, a high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN shall be installed upstream of the iodine filter.

9 KTA 1507 Page 9 (5) Separation efficiency and loading capacity of the filters shall be taken into account both for elementary iodine and for organically bound iodine when choosing the sorption materials. The iodine sorbents used shall be characterized by a low adsorption for noble gasses. The separation efficiency with respect to organically bound iodine is usually determined using methyl iodide as reference substance. (6) If low licensed limit values prevent performing a continuous measurement of the discharge of iodine-131 with the measurement equipment specified under paras. 1 through 5, application of a plant-specific monitoring procedure is permissible Detailed Assessment (1) The radioactive gaseous iodine discharged with the vent air shall be subjected to a detailed assessment. This requires that the radioactive gaseous iodine is accumulated by continuous deposition on an iodine filter. (2) Separation efficiency and loading capacity of the iodine filters shall be taken into account both for elementary iodine and for organically bound iodine when choosing the filters. (3) In order to prevent any falsification of the measurement values, a high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN shall be installed upstream of the iodine filter; this high-efficiency particulate air filter may be the same one as the one specified under Section (4) The accumulation period shall not exceed one week; the time elapsed between start of accumulation and start of measurement shall be accounted for by applying a corresponding correction for radioactive decay. (5) The activity of iodine-131 shall be determined by gamma spectrometric measurements within one day after taking the sample. (6) The high-efficiency particulate air filter and the iodine filter shall be analyzed without delay whenever the threshold value specified under Section para. 1 is reached and has registered for the duration of more than 30 minutes. (7) With regard to the detailed assessment of the activity of radioactive iodine, the detection limit of the measurement equipment shall not exceed Bq/m 3 with respect to the reference nuclide iodine-131. (8) The detailed assessment of the activity of discharged radioactive iodine shall, preferably, be carried out as specified in paras. 1 through 7. Alternatively, it may be carried out as specified in paras. 9 through 13, provided, one, that the activity concentration of iodine-131 in the primary cooling circuit is less the Bq/m 3 and, two, that emissions not accounted for by this procedure, e.g., from experiments, are verified as being negligibly small. (9) With regard to determining the discharged activity of iodine, representative water samples of the primary cooling circuit shall be taken in weekly intervals. (10) The activity of iodine-131 in the representative water samples shall be determined by gamma spectrometric measurements within one day after the samples were taken. A corresponding correction for radioactive decay shall be applied. (11) The detailed assessment of the radioactive iodine discharged with stack vent air shall basically be performed by multiplying the determined activity concentration of radioactive iodine in the primary cooling circuit by one-tenth (typical for research reactors) of the primary coolant volume that has evaporated during the period analyzed in the detailed assessment. It is permissible, alternatively, to base this detailed assessment of the radioactive iodine discharged with stack vent air on an experimentally determined coefficient accounting for the transfer of radioactive iodine from the primary cooling circuit to the stack vent air. (12) Whenever the threshold value under Section para. 1 is reached and has registered for the duration of more than 30 minutes, representative water samples from the primary cooling circuit shall, without delay, be taken and analyzed. (13) The detection limit of the measurement equipment for performing the measurement specified under para. 10 shall, when performing the measurement on a sample of demineralized water, not exceed a value of Bq/m 3 for the reference nuclide iodine Tritium Light water reactors (1) The activity discharge of tritium with vent air in the chemical form of water shall be monitored. This requires continuously accumulating air samples. (2) The samples shall be analyzed for the activity of tritium in quarterly intervals. This analysis may be carried out on the individual samples specified under para. 1 or on a representative mixture sample. (3) The analysis procedure shall be able to detect a tritium activity concentration as low as Bq/m 3 in the vent air. (4) If the type of sampling requires that the temperature and humidity of the vent air must be taken into account, then these parameters shall be determined in monthly intervals. (5) If molecular sieves are used to collect tritium, then a possible falsification of the measurement results by residual activity shall be taken into account. Once used molecular sieves should not be used a second time. However, if repeated use is intended, then, prior to deployment, the used molecular sieve shall be cleared of any residual water and shall be reactivated by subjecting it to a four hour long rinsing process in a stream of inert gas at a temperature of 400 C. (6) As an aternative to the requirements specified under paras. 1 through 5, the procedure described under paras. 7 through 9 may be used. (7) With regard to the detailed assessment of the activity discharge of tritium, the activity concentration of tritium in the pool water shall be measured once a year. (8) The activity discharge from tritium shall be calculated by multiplying the activity concentration of tritium determined for the sample with the amount of evaporated pool water. (9) The detection limit for the measurement of the activity concentration of tritium in the pool water shall not exceed a value of Bq/m 3. (10) If a light water reactor is equipped with an additional heavy water tank the tritium inventory of which could exceed Bq, then the requirements under Section shall be fulfilled Heavy water reactors (1) The activity discharge from tritium with vent air shall be monitored continuously with respect to a threshold value. The detailed assessment shall be performed as specified under Section paras. 1 through 5. (2) The measurement range of the measurement equipment shall enable monitoring discharge rates between Bq/h and Bq/h depending on the nominal volumetric flow of the vent air.

10 KTA 1507 Page 10 (3) The detection limit of the measurement equipment shall not exceed a value of Bq/m 3. (4) In order to prevent a falsification of the measurement values, a high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN shall be installed upstream of the measurement equipment. (5) The volumetric flow of the measurement air and of the counter gas shall be kept constant within the permissible deviation of ± 15%; they shall each be monitored by a flow rate meter with respect to their respective upper and a lower threshold values. 3.6 Radioactive Strontium (1) The radioactive strontium discharged with vent air shall be monitored by continuously accumulating the strontium by deposition on a high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN from a partial air stream of the vent air. This high-efficiency particulate air filter may be the same one as the one specified under Section (2) The analysis for strontium-89 and strontium-90 shall be performed in quarterly intervals on mixture samples that may be created from the high-efficiency particulate air filters exposed in that particular time period. The time elapsed between start of sampling and start of measurement shall be accounted for applying a corresponding correction for the radioactive decay of strontium-89. (3) The activity of radioactive strontium isotopes discharged with vent air shall be subjected to a detailed assessment. The detection limit regarding the detailed assessment of the discharged activity of strontium-89 and strontium-90 shall not exceed a value of Bq/m 3. (4) The detailed assessment specified under paras. 1 through 3 may be dispensed with, provided, one, the activity concentration of lanthanum-140 (as reference nuclide) from the detailed assessment of radionuclides bound to aerosol particles under Section does not exceed a value of Bq/m 3, two, the discharge of strontium-89 and strontium-90 from carrying out experiments is verified as being negligibly small. 3.7 Alpha Emitters (1) The alpha emitting radioactive substances (alpha emitters) discharged with vent air shall be monitored by continuously accumulating the alpha-emitters by deposition on a highefficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN from a partial air stream of the vent air. This high-efficiency particulate air filter may be the same one as the one specified under Section (2) The nuclide-specific analysis for alpha emitters shall be performed in quarterly intervals on mixture samples that may be created from the high-efficiency particulate air filters exposed in that particular time period. (3) The activity of alpha emitters discharged with the vent air shall be subjected to a detailed assessment. In this assessment the radionuclides listed in Table 3-3 shall be taken into account. The detection limit of the measurement equipment shall not exceed a value of Bq/m 3 with respect to americium-241. Any undetected radionuclides of Table 3-3 shall be listed with the value of the decision thresholds and detection limits achieved in the individual measurement with the measurement equipment. The nuclide pair plutonium-238 and americium-241 as well as the pair plutonium-239 and americium-240 may be summed up together in the detailed assessment. (4) Any additional alpha-emitting radionuclides verified in the vent stack air shall be individually recorded in the report form (cf. Figure 8-1) under the heading "Other α-emitting radionuclides". (5) The detailed assessment specified under paras. 1 through 3 may be dispensed with, provided, the total alpha activity concentration in the primary cooling circuit does not exceed a value of Bq/m 3 and the discharge of alpha emitters from carrying out experiments is verified as being negligibly small. The total alpha activity concentration shall be determined in quarterly intervals from representative mixture samples. Uranium-234 1) Plutonium-238 Plutonium-239 Plutonium-240 Radionuclides Americium-241 Curium-242 Curium-244 1) Used instead of curium-242 and curium-244 in case of research reactors with highly enriched nuclear fuel Table 3-3: Radionuclides to be taken into account in the detailed assessment of the activity of alpha emitters discharged with vent air 3.8 Carbon-14 (1) The carbon-14 discharged with vent air in the chemical form of carbon dioxide shall be monitored. For this purpose, carbon-14 samples shall be accumulated continuously. The analysis for carbon-14 shall be performed in quarterly intervals by evaluating mixture or cumulative samples. The analysis procedure shall be able to detect a carbon-14 activity concentration of as low as 5 Bq/m 3 in the vent air. (2) The monitoring specified under para. 1 may be dispensed with, provided, the activity discharge of carbon-14 is assessed in detail by another determination procedure, e.g. one that is based on calculating the production rate of carbon Sampling (1) The location and procedure of sampling pipes shall be chosen such that the samples taken there are representative for emission monitoring. The objective must be that a homogenous mixture of the vent air has been achieved in the region where sampling is carried out. (2) The volumetric flow of the partial air stream directed out of the vent air shall normally not be less than one thousands of the nominal volumetric flow rate of the vent air. Details regarding sampling are specified in DIN ISO (3) The sampling pipes shall be designed, routed and fabricated of such materials that aerosols and other gaseous radioactive iodine compounds are retained as little as possible. Details regarding the design are specified in DIN ISO (4) The sampling equipment shall be designed or housed such that its temperature cannot fall below the dew point. (5) Selection and storage of the adsorption material for filters shall take ageing effects of the material into account. The temperature shall be kept within the specified range. (6) In the design of a filter bracket, it shall be considered a) that during operation its leak-tightness is such that the volumetric flow of leakage air is negligibly small relative to the partial volumetric flow for sampling,

11 KTA 1507 Page 11 b) that any damage of the filter in the area of the filter gasket is avoided, c) that any bypass flow around the filter is avoided, d) that the filter can be changed easily and, to a large extent, without danger of contamination, e) that it is corrosion resistant and easy to decontaminate. (7) In the case of non-continuous sampling, the point in time and duration of the sampling shall be chosen such that the individual samples are representative for the amounts of radioactive substances discharged between two consecutive samplings. (8) The sampling equipment for the continuous sampling of radionuclides bound to aerosol particles shall be designed such that during specified normal operation a spectrum of particles with aerodynamically equivalent diameters in the range between 0.1 µm and 20 µm is covered. The overall dissipation factor of the actual sampling equipment shall be determined by one of the following procedures: a) The overall dissipation factor of radionuclides bound to aerosol particles may be determined using test aerosol particles where the particle size of the specific material type (number and mass of the test aerosol particles) has a median value with an aerodynamically b) equivalent diameter of approximately 1 µm with a geometric standard deviation between 2 and 3. These test aerosol particles shall be fed into the vent air duct and the overall dissipation factor determined from the amount supplied and the amount found on the accumulating medium. c) The overall dissipation factor of radionuclides bound to aerosol particles may be determined by feeding the test aerosol particles into one of the sampling probes and calculating the pipe factor. In this case, the other parameters required for determining the overall dissipation factor shall be determined by individual measurements or calculations. d) The overall dissipation factor of radionuclides bound to aerosol particles may be determined by comparing the activity concentration measured directly in the vent air stack with the activity concentration determined from the measurement values of the accumulating and measurement equipment. (9) The overall dissipation factor shall be determined a) during commissioning of the sampling equipment, b) after any alteration of the sampling equipment that could essentially influence the overall dissipation factor, and c) regularly after every ten years. (10) The overall dissipation factor determined as specified under para. 9 shall be taken into account in the detailed assessment of the activity discharge of radionuclides bound to aerosol particles. Notes: (1) Aside from the gamma-radiating radionuclides, the radionuclides bound to aerosol particles also comprise the strontium isotopes Sr-89 and Sr-90 and the alpha-emitting radionuclides. (2) The detailed assessment includes the overall loss factor from calculating the activity disposal, as well as the decision threshold and the lower detection limit Non-central Monitoring of Emissions General requirements In research reactors radioactive substances may be produced in rooms and parts of the facility or may be transported to locations that are not connected to the central vent air stack. The discharge path of these radioactive substances ("non-central monitoring of emissions") shall be properly documented for the individual facility or task Monitoring The discharge of radioactive substances from the facilities or during the tasks specified under Section shall be monitored. This requires that representative monthly samples are taken from suitable locations and at times that are representative for the respective operating period; these samples shall be subjected to a nuclide-specific analysis. The annual activity discharge shall be estimated on the basis of this analysis and shall be documented in the annual report. The essential requirements of Section 3 are collated in Table 3-4.

12 KTA 1507 Page 12 Measurement Task Measurement Procedure Measurement Range Detection Limit Reference Nuclide Remarks Noble gasses Continuous measurement Detailed assessment total β-activity nuclide specific γ- activity 1) Bq/m 3 Xe Bq/m 3 Xe-133 The threshold value is oriented on the value of the licensed discharge. If Xe-133 but no Kr-85 is detected, then the measurement for Kr-85 shall be repeated after a period of at least two days. Radionuclides bound to aerosol particles Continuous measurement Detailed assessment total β-activity or total γ-activity 4 (Bq/m 3 ) h Cs-137 deposition on filter Bq/m 3 Co-60 The continuous measurement may be dispensed with, provided, a continuous measurement of radioactive iodine is performed or the radionuclides bound to aerosol particles are retained by filtering the entire exhaust air and the proper functioning of the retaining equipment is monitored. Iodine Continuous measurement γ- activity 2 (Bq/m 3 ) h I-131 Detailed assessment Tritium deposition on filter Bq/m 3 I-131 sampling of water Bq/m 3 I-131 Detailed assessment on the basis of evaporation if the activity concentration of I-131 in the water sample is less than Bq/m 3 Light water research reactors Detailed assessment accumulation in collector Bq/m 3 H-3 sampling of water Bq/m 3 H-3 Alternative measurements in the pool water are permissible Heavy water research reactors Continuous measurement β-activity Bq/h to Bq/h Bq/m 3 H-3 Detailed assessment accumulation in collector Bq/m 3 H-3 Strontium Detailed assessment deposition on filter Bq/m 3 La-140 The detailed assessment may be dispensed with, provided, one, the activity concentration of La-140 (reference nuclide) from the detailed assessment of radionuclides bound to aerosol particles does not exceed Bq/m 3 and, two, the discharge of Sr-89 and Sr-90 from carrying out experiments is verified as being negligibly small. Alpha emitters Detailed assessment deposition on filter sampling of water Bq/m 3 Am Bq/m 3 Am-241 The high-efficiency particulate air filter shall basically be analyzed for alpha emitters, cf. Section 3.7 para. 2. The detailed assessment may be dispensed with, provided, one, the total alpha activity concentration of alpha emitters in the primary coolant circuit does not exceed Bq/m 3 and, two, the discharge of alpha emitters from carrying out experiments is verified as being negligibly small. Carbon-14 Detailed assessment accumulation in collector 5 Bq/m 3 Accumulation of carbon dioxide. Other determination procedures are permissible. 1) Upper limit of measuring range shall be at least one tenth of the annual licensed limit value averaged over 24 h. Table 3-4: Monitoring of the discharge of radioactive substances with exhaust air during specified normal operation

13 KTA 1507 Page 13 4 Monitoring the Radioactive Substances Discharged with Vent Air during Design Basis Accidents 4.1 General Requirements (1) During and after design basis accidents the discharged radioactive substances shall be determined according to kind and activity in accordance with the requirements specified in this Section 4. With regard to the measuring procedures and the radiological relevance of the discharged radioactive substances, the following nuclides and nuclide groups shall be differentiated between: a) radioactive noble gasses, b) radionuclides bound to aerosol particles, c) radioactive gaseous iodine, d) tritium. (2) If it is verified by design basis accident analyses that the design basis accident related activity discharge from individual or all of the nuclide groups specified under para. 1 a) cannot lead to an exceedance of the licensed annual limit values and b) will be monitored during a design basis accident by the measurement equipment of specified normal operation and this monitoring is in accordance with the requirements for the measurement equipment for monitoring the discharge of radioactive substances with vent air, then, no additional measurement equipment for the respective nuclide groups is required. (3) The continuous or non-continuous sampling and measurements necessary for monitoring the discharge of radioactive substances shall normally be carried out in a partial air stream of the vent air. (4) The volumetric flow of vent air shall be continuously measured and recorded. (5) The volumetric flows of the partial air streams of the vent air shall be monitored; a drop of the volumetric flows of the partial air streams below a threshold value shall set off an alarm in the display area of the control room dedicated to emission monitoring. (6) If it cannot be precluded for the measurement equipment for monitoring the discharge with stack vent air that they might fail due to effects from design basis accidents (e.g., fire), it shall be ensured that alternative monitoring can be carried out without delay, e.g., non-continuous sampling. This requires that corresponding sampling points are provided, e.g., in the exhaust gas duct or in the base of the exhaust gas stack. (7) With respect to the analysis of gaseous samples, of the aerosol and the iodine filters, suitable procedures and measurement equipment in the laboratory shall be provided taking the maximum expected activity of the samples into account. 4.2 Radioactive Noble Gasses Continuous measuring (1) The activity discharge rate of the radioactive noble gasses discharged with vent air shall be continuously determined by measuring the activity concentration in the vent air and measuring the vent air s volumetric flow. (2) The total beta activity concentration of the radioactive noble gasses shall be determined from a measurement of the total beta activity. (3) For the purpose of measuring the activity concentration, one filter with a retention level of at least 90 % for elementary iodine and one high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN shall be installed upstream of the measurement chamber to prevent its contamination. (4) The detection limit of the measurement equipment for measuring the activity concentration shall not be higher than one thousands of the licensed annual limit value with respect to the vent air volume discharged in a 24 h period. (5) Design basis accident analyses shall be performed in order to specify the end points of the measurement range. The resulting maximum activity concentration of radioactive noble gasses in the vent air multiplied by a safety margin of 10 shall normally still be within the measurement range of the measurement equipment. (6) An activity measurement equipment for specified normal operation as specified under Section may be used instead of the measurement equipment specified under para. 2, provided, the former is designed to be redundant and also fulfills the requirements of this Section Detailed assessment (1) The nuclide composition of radioactive noble gasses discharged with vent air shall be determined by gamma spectrometric measurements. (2) In case the nuclide composition of radioactive noble gasses is determined non-continuously, representative samples shall basically be taken from the onset of a design basis accident on, as far as possible, in hourly intervals for as long as a design basis accident related release in exceedance of the licensed limit value for specified normal operation must be expected; these samples shall be analyzed without delay. It is permissible to take samples and perform nuclide-specific measurements in longer time intervals than one hour, provided, the measurement value at the noble gas measurement equipment specified under Section indicates that no essential changes have occurred. (3) In the case of a non-continuous determination of the nuclide composition, the activity discharge of individual radioactive noble gas nuclides shall be determined based on the activity concentration determined with the measurement equipment specified under Section para. 2. (4) The nuclide composition of radioactive noble gasses may also be determined by continuous nuclide-specific measurements. 4.3 Radionuclides Bound to Aerosol Particles (1) For as long as it must be assumed that a design basis accident related discharge of radionuclides bound to aerosol particles can occur that exceeds a licensed limit value for specified normal operation, the activity of the individual radionuclides bound to aerosol particles discharged with vent air shall, as far as possible, be determined in hourly intervals by gamma spectrometric measurements. (2) For the purpose of determining the nuclide composition of the radionuclides bound to aerosol particles, these substances shall be continuously accumulated from a partial air stream by deposition on a high-efficiency particulate air filter of at least Filter Class E12 in accordance with DIN EN This sampling equipment may be the same one specified under Section for the detailed assessment of radionuclides bound to aerosol particles during specified normal operation, provided, this equipment also fulfills the requirements of this Section 4. (3) During accumulation of radionuclides bound to aerosol particles, the volumetric flow of the partial air stream shall be measured, and any deviation by more than 20 % from its nominal value shall set off an alarm (in the control room).